The long awaited Ontario Court of Appeal decision Westerhof v. Gee Estate has finally been released. This appeal raises the question of whether Rule 53.03 applies only to litigation experts or whether it applies more broadly to all witnesses with special expertise who give opinion evidence.
The Court of Appeal rejected the Divisional Court’s conclusion that the type of evidence – whether fact or opinion – is the key factor in determining to whom Rule 53.03 applies. The Court of Appeal held that treating experts and non-party experts (ie. accident benefits assessors) may give opinion evidence for the truth of its contents without complying with Rule 53.03 where:
• The opinion to be given is based on the witness’s observation of or participation in the events at issue (ie. treatment); and
• The witness formed the opinion to be given as part of the ordinary exercise of his or her skill, knowledge, training and experience while observing or participating in such events.
The Court noted that if the treating experts or non-party experts also proffer opinion evidence extending beyond the limits described above, they must comply with Rule 53.03 with respect to the portion of their opinions extending beyond those limits. As with all opinion evidence, trial judges must retain its gatekeeper function with opinion evidence and assess its admissibility based on the established test.